CCU - Will not process with vmover if machine is in target domain

I have an issue here with CCU

The scenario is a multi-user machine on VPN.

When user 1 gets migrated, the user and the machine are both in the source domain.

CCU will kick in, do it's vmover thing and rejoin / reboot, all good.

Now the second user is set to be migrated. 

Now the user is in the source domain, but the machine is already in the target domain. 

When I push the MSI, it installs and starts fine - but then it immediately stops and uninstalls itsself, without processing the user profile / data.

The log only shows "is target domain" - and checking the "backup domain" it only rightfully states "is not source domain". 

This happens no matter if I set the MSI property "MOVE_ENABLE" to 1 or 0. 

The property "PREPROC_ENABLE" is set to 1.

Any ideas what else I can try to handle this scenario?